1. Field of the Invention:
This invention relates to anti-inductive structures, and more particularly to a light-weight gasket for use as an EMI seal.
The design of electronic equipment cabinets, particularly cabinets housing computer and other commercial equipment operating in a controlled environment, has moved in recent times toward the use of lighter weight structures. The use of structural foam and composition board for panels and doors is one example of this trend. EMI shielding for such structures must of course undergo a commensurate decrease in weight, without reduced performance.
The EMI shields of equipment enclosures exhibit discontinuities at covers, doors, panels, ventilating openings and the like. One of the most important elements of the EMI shield is the gasket means utilized for "sealing" the discontinuities to prevent undesirable EMI leakage. Such seals usually take the form of electrical conductors bridging or short circuiting the discontinuities.
2. Description of the Prior Art
Prior art EMI seals or gaskets consist of spring-tempered metal (e.g., brass, Phosphor-bronze, beryllium-copper or the like) usually formed into a plurality of bridging conductors termed finger stock or coil stock. Spring-tempered metal gaskets require substantial pressure exerted thereon in order to establish reliable electrical contact between the elements of an EMI shield, through the fingers or coils interposed between the elements. Such pressure was readily supplied by the latching or dogging of relatively heavy closures. Further, it was often necessary to support or attach elements of the gasket to the enclosure by means of heavy metal support bars or clamps and the attendant fastening hardware.
With the advent of light weight enclosure elements there arises a need for a light-weight reliable EMI gasket.